Colored Diamonds for Inspecting Magnetic Fields in Superconductors

Like many other gemstones and mineral, diamond can come in many colors, depending on the impurities it contains. When we learned how to synthesize diamonds, we also learned how to control their color by injecting different atoms, and as it turns out special properties can come with those colors. Now researchers at the Universities of California, Berkeley and Los Angeles, and Ben-Gurion University of Negev want to use one of those special properties to probe high temperature superconductors with unprecedented accuracy.

By bombarding a synthetic diamond with nitrogen atoms, it is possible to knock out some of the carbon atoms, either leaving a nitrogen atom in its place, or an empty hole. Heating the diamond can allow the holes and nitrogen atoms to move around and pair up, creating nitrogen-vacancy centers. These regions are very sensitive to magnetic fields and obey quantum mechanics, which lends to their sensitivity. The researchers are using this sensitivity by building magnetic field sensors with them and connecting them to a chip along with a high temperature superconductor. As the temperature drops, the researchers can watch as the magnetic field vanishes, signaling the transition to superconductivity.

At the same time the material became superconducting, the researchers also caught magnetic vortices forming and disappearing. The researchers hope to use the diamond-based sensor to learn more about those vortices, and how they may impact superconductivity and superconductors.